The present invention relates to the slaughtering of animals. More particularly, the present invention relates to a method for the killing of slaughterhouse animals by bleeding whereby the blood may be collected in a substantially sterile state.
The current slaughterhouse killing of animals involves exsanguination preceded by stunning. In the method, the animal, e.g. steer, heifer, or other such animal, is driven through a chute into a stunning stall. The animal is stunned by one of several techniques, all designed to render the animal unconscious but still alive without any penetration of the animal's body. Following removal from the stall, the animal is suspended by its hindlimbs and an incision is made generally in the midline from the manubrium to the ventral base of the neck to expose the anterior wall of the thorax. Entrance is then made into the thorax by cutting through the hypaxial muscles which form the anterior chest wall. This incision is then followed by the passage of the knife through a "window" formed laterally by the first pair of sternal ribs, ventrally by the manubrium and dorsally by the thoracic vertebrae and hypaxial musculature. The large vessels in the anterior mediastinal space are incised en masse by this last incision. In this bleeding procedure, blood from the animal pools in the anterior chest, flows out the incision, down the animal's neck and collects on the floor of the slaughterhouse.
The above described bleeding procedure suffers from several major disadvantages. For one, the large amounts of blood produce a waste stream from the slaughterhouse with extremely high levels of biochemical oxygen demand (BOD). For example, the average beef-slaughtering plant produces 12 to 16 pounds of BOD per head per day. It is estimated that at least 25% of the BOD attributable to the slaughtering and packing of beef is accounted for by the blood loss described above. Environmental laws, both national and local, generally require that animal processing wastes from slaughterhouses undergo treatment prior to discharge into surface streams, i.e. the BOD load must be reduced to suitable levels. It will be readily recognized that in a large slaughterhouse, such prior treatment is expensive and time consuming. Indeed a plant processing 1000 head/day would require about 10 MGD of dilution water to reduce the BOD of the waste-water to an acceptable level. Over and above the environmental problems caused by blood losses in the slaughterhouse, the conventional bleeding procedures represent the loss of a potentially valuable by-product, i.e. edible blood protein. The dry weight mass of blood is comprised of about 95% protein. In a world where protein adequate diets are becoming a rarity, especially in developing countries, and where providing meat to satisfy such diets is not economically feasible, it is imperative that alternate sources of high quality protein be found. Edible blood protein derived from slaughterhouse blood potentially provides an excellent and inexpensive food additive of wide applicability and is an attractive alternate to costly, high protein foods. While there are current procedures for collecting blood from slaughterhouses for use in the production of products for food purposes, such methods are time consuming and not amenable to high production rates. Additionally, extracted blood is an excellent growth medium for bacteria, molds, fungi, and viruses. The most generally used methods of blood collection permit the blood to be exposed to the atmosphere for considerable lengths of time thereby incurring the possibility that the blood will be contaminated and rendered unfit as a food additive. Additionally, currently used methods still permit the possibility of blood fouling of slaughterhouse floors. Also, most collection methods currently used are so time-consuming as to preclude wide-spread use in large slaughterhouses.